Light emitting diodes (LED or LEDs) are solid state devices that convert electric energy to light, and generally comprise one or more active layers of semiconductor material sandwiched between opposed doped layers. When a diode is forward biased (switched on), electrons can recombine with holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. LEDs are monochromatic light sources and the production of white light requires the use of color mixing such as blue LED produced by Gallium Nitride combined with a phosphor layer. White light is produced from the absorption of blue light and re-mission into yellow light by phosphor, as well as the subsequent mixing of yellow and blue light.
Incandescent (INC) omnidirectional lamps are the most common lighting sources in use today. Incandescent lamps produce light through the process of incandescence, whereby electricity passing through a tungsten filament causes it to heat up and produce visible light. Over time the filament material can evaporate and deposit onto the inner surface of the glass bulb. Halogen lamps have overcome this problem by using halogen elements in combination with evaporated tungsten and depositing back onto the filament, allowing a smaller form factor than traditional INC lamps. Halogen lamps produce a large amount heat with most of the radiation produced in the infrared region. LED technologies or Solid-State Lighting (SSL) present significant advantages compared to these alternative lighting solutions in respect of their operating principle, electrical efficiency, economical value, and environmental impact. In many applications, several LED dies or chips are mounted within an LED package or on an LED module, which may make up part of a lighting unit, lamp, or bulb. An LED bulb may be made with a form factor that allows it to replace a standard threaded incandescent bulb or any of various types of fluorescent lamps, achieving similar performance using a fraction of the power.
Consumer satisfaction is an important factor affecting the rate and scope of any lighting solutions market transformation. This is evident through the collective experience with compact fluorescent lamps (CFLs) where public perceptions were severely tainted by early customer experiences with poor quality products based on performances such as color, flicker, noise, lack of intensity control, and early failure. The introduction of LED lighting products into the consumer market has produced both high and low-quality lamps. Some can replace incandescent lamps with little or no noticeable difference, while others fall short on certain performance attributes and thus do not make suitable replacement products. Manufacturers have reportedly used the highest quality LEDs for photometric testing, only to use lower quality LEDs for bulk manufacture [Southern California Edison. (August 2009). LED MR16 Lighting. ET 07.14 Report]. Most of the currently available replacement lamps in the market produce significantly poor color rendering compared to incandescent lamps.
The importance of reducing energy use for both environmental and economic reasons is apparent to everyone. Under the assumption of a large commercial acceptance rate, LED “bulbs” have the potential to cut lighting loads in the United States by nearly one half by 2030 (Department of Energy, 2012). There is widespread recognition that only high-quality products will deliver the market acceptance required for broad adoption of LED lighting solutions. Residential consumers are accustomed to high CRI sources, as incandescent lamps (with 100 CRI) are the predominant lamps in the residential sector. CRI is a measure of how accurately a light source renders the colors of the objects being illuminated, compared to a reference light source of the same color temperature. Therefore, the goal of many SSL programs is aimed at accelerating development, demonstrating technologies, and formulating performance standards, regulations, labeling, and certifications. Industry bodies for LED Standardization in the US include Professional Associations, Standards Organizations, Trade Organizations, Government Agencies: Illumination Engineering Society of North America (IESNA), Institute of Electrical and Electronic Engineers (IEEE); Underwriters Laboratories (UL), American National Standards Institute (ANSI); National Electrical Manufacturers Association (NEMA); Department of Energy (DOE), Environmental Protection Agency (EPA), Energy Star Program; U.S. Standard Organizations; Organizations developing LED Lighting Safety Standards; U.S. Government Regulations and LED Programs; Federal and local government regulatory positions. From an industry perspective, standards and regulations provide a platform for consistent language of definitions, test methods, laboratory accreditation and for product design, manufacturing and testing. From a governmental perspective, regulation helps ensure public safety, provides consumer protection, regulates energy consumption and monitors environmental issues.
Federal and State (local) government regulations have established standards, voluntary and mandatory, for SSL products, and provide incentives such as financial investment, loans, and grants, to encourage development and deployment of SSL products meeting such standards to replace or retrofit conventional lighting products. For example, the State of California has established the 2016 Building Energy Efficiency Standards (effective Jan. 1, 2017) representing a major step towards meeting California's residential Zero Net Energy (ZNE) goal by the year 2020. California has had a long history of energy efficiency leadership including state appliance standards since 1976 (Title 20), building energy efficiency standards since 1978 (Title 24, part 6) and mandatory and voluntary green building standards since 2008 (CalGreen or Title 24, part 11). State energy policy calls for all new homes to be Zero Net Energy (ZNE) by 2020, and all new commercial buildings to be ZNE by 2030. All residential buildings that are regulated occupancies must be designed and built to comply with the mandatory measures of Title 20 (certification of individual products) and Title 24 (building code requiring JA8 certification of light sources). Reference Joint Appendix JA8 regulations now set quality standards for certain types of high efficacy lamps and luminaires installed in residences, regardless of source type. Title 20 standard aims to ensure a minimum level of LED replacement lamp quality to build and maintain consumer satisfaction with LED lamps. To do this, the standard aims to set requirements that result in LED lamps with performance characteristics that are virtually indistinguishable from those of the incandescent lamps they are designed to replace. For compliance, products must conform to many requirements, including, but not limited to, lumen output, efficacy, color quality, color consistency, power factor, light distribution, power spectral distribution, lamp flicker, dimming performance, and lumen maintenance (hrs) lifetime.
As a lamp ages, for various reasons it produces less light but continues to consume the same amount of power. Lumen depreciation for LED packages is affected by operating conditions and varies substantially between different products. Temperature has a significant effect on the deterioration of LEDs, with most of the input energy being converted into heat (US DOE, 2007. Thermal Management of white LEDs), whereby higher temperatures result in higher levels of degradation. The ability of an LED replacement lamp to manage heat affects its performance, lumen output, CCT, longevity (lumen maintenance), and safety. LED is a semiconductor device that has a low melting temperature and therefore requires heat transfer to keep the junction temperature below a certain temperature limit (typically 125° C.). Thermal management techniques include the use of active and predominantly passive heatsinks employing fins to increase the surface area for heat dissipation to remove heat from the LED junction. Mass has been considered as an indicator of lamp quality, whereby a larger quantity of fin materials translates into more effective heatsinks and ultimately smaller changes in luminous flux over time. However, the design of LED retrofit lamps or bulbs is constrained by the form factors of INC or halogen lamps (e.g., MR16), stipulated by standards, for example, ANSI 78.24, to fit within standard luminaires. The lack of space for accommodating a large heatsink in an E26 light bulb is a major constraint for LED product design. The form factor of most LED lamps has evolved, becoming lighter and smaller, in part due to increasing efficacy, which in turn results in less mass and/or volume needed for thermal management. LEDs require a power supply (commonly called a “driver”) or LED ballast. The power supply converts line (AC) power to the appropriate DC voltage (typically between 2- and 4-volts DC for high-brightness LEDs) and current (generally 200-1000 milliamps, mA), and may also include supplementary electronics for dimming and/or color correction control. Innovative lamp manufacturers employ several solutions for thermal management, including improved drivers, reducing power losses of components, forced convection methods, improved heat sink designs, and advanced materials. However, it has been a challenge for manufacturers to meet standards, especially lumen maintenance lifetime for miniature LED lamps or packages under form factor constraints for retrofitting or replacement of various standard INC, halogen lamps, and luminaires.
Through applied effort, ingenuity, and innovation, Applicant has identified deficiencies and problems with existing integrated and retrofit LED packages, lamps, or bulbs to meet existing standards. Applicant has developed a solution that is embodied by the present invention, which is described in detail below.